7. UV Light: This early hypothesis sought to
explain both the LR active response and the lack of organics reported by
the GCMS. An experiment at Viking Landing Site 2 eliminated this
possibility. Before dawn, the sampling arm moved a rock before the sun's
rays could strike it. A sample of soil that had underlain the rock and
thus was protected from UV for eons was taken and promptly delivered to
the instrument. Despite the absence of any UV exposure, the sample
produced a positive LR response, essentially identical in kinetics and in
magnitude to those of the Viking Lander 1 positive response seen in FIG.
1. This direct experiment carried out on Mars eliminated the possibility
that UV light was the cause of the activity detected by the LR experiment
on Mars.

8. Clays: It was proposed84,85,86
that clays on Mars reacted with the LR nutrient to produce labeled
CO2 . Various clays were proposed in sequence as experiments
detected deficiencies in duplicating the LR results. The clays, in turn,
ranged from montmorillonite to nontronite to palagonite to smectites. The
experiments suffered from basic problems87 including the
failure to sterilize the samples tested or to use sterile procedures in
the experiment in order to exclude biological effects from microorganisms
in the clays. Extreme pHs were imposed to obtain responses and the
responses did not have the kinetics of the LR positive responses. Data
replicating the thermal sensitivities of the LR active agent at the lower
levels of 50░C and 10░C were not forthcoming. Perhaps most important to
the interpretations was the fact that the responses were not normalized to
those from the Viking LR instrument. The counting efficiency used on the
clays was 75% compared to 3% for the LR. Hence all responses for the clays
should have been reduced by a factor of 25, which would have placed them
in the control or noise levels. In the last work cited above, the claims
of replicating the LR data were reduced to state that "iron-enriched
smectites . . . were shown . . . to simulate many of the findings of the
Viking Labeled Release Experiments on Mars." Considering that there is no
direct evidence for clays on Mars, and the flawed nature of the
experiments, the possibility that clays explain the LR Mars data seems
vanishingly small.

9. Complexities of Independent Origin of Life:
While listed last, this is really the penultimate reason responsible for
discounting the LR Mars data as evidence for life. The origin of life is
so poorly understood that the complexity posed by it alone would make the
application of Ockham's Razor favor a non-biological explanation of the LR
data. However, the presumed evidence of microbial life in the two martian
meteorites raises the possibility that an independent origin of life on
Mars was not necessary for life to exist on that planet. If the biological
fossils are confirmed, the principle of panspermia will be established.
EETA79001 is only 600,000 years old, in effect, of the "modern" era on
Mars. The environmental changes deemed by many as inhospitable to life
already had occurred. Were microorganisms alive so recently, their
survival to the present would be readily inferred.

The presence of microorganism fossils in the martian
meteorites would also make a case against the oases theory88
which proposes that microorganisms may currently exist only in pools of
liquid water postulated deep beneath the surface. Analysis89 of
the physics of ejection of planetary material by meteoric impact concludes
that materials escaping planetary gravity originate from, or near, the
surface of the impact area. Thus, any fossils with the meteorites that
fell on Earth could not be from deep oases. Furthermore, were there deep
sites of living microorganisms, it is likely that volcanic action, frost
heaving, or other mechanisms would eject such material to the surface.
There any microorganisms could be widely distributed by the winds. The
microorganisms might adapt to or become lyophilized by the surface
conditions. Either way, they might still respond in the manner detected in
the LR instrument upon being moistened with liquid nutrient under benign
conditions. Regardless, the meteorites provide a now plausible vehicle for
ejection into space, lyophilization by the space environment, survival of
re-entry, and thus, interplanetary transportation of living
microorganisms. The independent origin of life on Mars is no longer a
barrier to acceptance of the LR data as evidence for life.

3.
CONCLUSION

Many hypotheses
have been advanced and tested in attempts to account for the
well-characterized activity detected in the surface material of Mars by
the LR experiment. As shown above, these hypotheses have themselves been
found wanting. The demonstrated success of the LR and the exquisite
sensitivity with which it has detected microorganisms during its extensive
test program with its record of no false positives can no longer be
denied. No non-biological approach published, or known to the author, has
duplicated the LR Mars data. Some laboratory experiments have produced
positive responses, but the detailed thermal sensitivity exhibited by the
variety of controls conducted on Mars has remained elusive in all such
tests compatible with martian conditions. On the other hand, a combination
of known properties of microorganisms, perhaps even those possessed by
single species, could reproduce all aspects of the LR data. The biological
interpretation of the Mars LR results is left standing alone. Recent
discoveries of life forms thriving in extraordinarily severe environments
on Earth strongly indicate that any alien organisms arriving on Mars might
well and widely adapt to their new home. Application of the scientific
principle leads to a conclusion:
the Viking LR experiment detected
living microorganisms in the soil of Mars.

4.
RECOMMENDATIONS

1. Add
Life Detection Tests to Planned Missions. The above conclusion will
require independent experimental confirmation before achieving general
acceptance. No life detection experiments are planned for the NASA's 10
Mars landers scheduled over the next decade. However, it is still possible
to add life detection capability to them within the new NASA paradigm of
"cheaper, smaller, faster." Even without a dedicated life detection
experiment, it is possible that confirmation of extant life may be
achieved.